program Four;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
n, k, i, nf, kf, rf, a: integer;

begin
  readln (n); // n>k
  readln (k);
  nf:=1;
  kf:=1;
  rf:=1;
  for i:= 1 to n do
    nf:=nf*i;
  for i:= 1 to k do
    kf:=kf*i;
  for i:= 1 to n-k do
    rf:=rf*i;
  a:=nf div(kf*rf);
  writeln(a);
  readln;
end.
 